@mountainchris I am not having any issues here. There are 2 ways to use the smart sensor without the watch on you.
#1. Put the Smartsensor on, start an activity on the watch and leave the watch at home, in a locker, etc. The smartsensor will record 2-3h without the watch. Get the watch, end the activity and HR will sync.
#2. Use SA on the phone but the phone must stay with you, there is no memory feature in SA.
Both work for me.